There are various types of detectors currently in use for the detection of ionizing radiation such as x-rays and gamma rays. The scintillation type of detector responds to an x-ray photon by producing a flash of light from an ionizing event occurring in the detecting material, and uses a photomultiplier tube to detect and amplify the light pulse. In another type of solid state detector the charge generated in the material itself is collected and registered in an external circuit.
Such detectors rely on the principle that a photon of the ionizing radiation will impart sufficient energy to an atom or molecule of the radiation detecting substance to raise its energy level from the ground state to higher level, with a subsequent return to the ground state providing a detectable event.
One drawback of present radiation detectors is that the energy required to produce an excited state is of the order of one electron volt. This limits the ultimate resolution of an energy measurement to one electron volt.
Superconductors, on the other hand, depend upon charge carriers that are very weakly bound. As superconducting materials are cooled to the superconducting state, the current carrying electrons condense into Cooper pairs. Their binding energies are in the millielectron volts range. As a consequence, if the bonds of the Cooper pairs in a superconducting material are broken in response to the presence of ionizing radiation and if such a change can be detected, then enhanced energy resolution measurements of radiation in the millielectron volts range can be realized.